Jailbreak iPhone 3GS with iOS 6.1.3 version
iOS 6.1.3 is jailbreakable to iPhone 3GS!
Good news for all iPhone 3GS users about the iOS 6.1.3 version, you will be able to jailbreak it either tetheredly or untetheredly!
Few days ago, Apple released the new iOS 6.1.3 version and many people are confused if they should upgrade their devices with this iOS version. The evasi0n tool is no longer able to jailbreak the iOS 6.1.3 version because Apple managed to patch the exploits the Evasi0n tool was using. Some models can still be jailbroken if they already have the iOS 6.1.3 version, but unfortunately not all iDevices.
Why iOS 6.1.3 version can be jailbroken on iPhone 3GS?
The truth is that all iDevices that have the A4 chip on them can be jailbroken even if they upgraded to iOS 6.1.3 version. This means that iPhone 3GS, iPhone 4 and iPod Touch (the older versions) support iOS 6.1.3 version and a jailbreaking solution exists.
The special think about iPhone 3GS is that it has two bootrom versions, the old and the new. If you own an iPhone 3GS with an old bootrom you are twice lucky, because you can jailbreak iOS 6.1.3 version and you can do it untetheredly. All the other A4 chip devices can be jailbroken as well, but with a tethered jailbreak. This means that you have to plug your device to your computer every time you need to reboot it, and complete the rebooting process with the help of Redsn0w tool.
Some final words about iOS 6.1.3 version!
To sum up, you should only upgrade to iOS 6.1.3 version if you REALLY need to use Cydia and your iDevice has a A4 chip. All other iDevices cannot be jailbroken, and no further news got public from the jailbreaking community.
All iPhone 3GS users with an old bootrom can safely upgrade to iOS 6.1.3 version and their jailbreak will be untethered!